1. Field of the Invention
The present invention relates to a light activated switching means and more particularly, but not by way of limitation, to light activated switching means having selective timing means in conjunction with photosensitive blocking circuits to protect against triggering by unwanted ambient or stray light sources.
2. Description of the Prior Art
The marked increase recently in the crime rate, relating primarily to burglaries and muggings has given rise to the need for protecting homeowners and individuals when they arrive at home late at night. It has been asserted that one of the primary settings for crimes of this nature is darkness and there has been a distinct need for apparatus to provide lighting when an individual approaches a darkened house at night. Naturally, there is an added advantage, that being the prevention of accidents.
This increased crime rate has also affected stores which normally have minimal lighting at night after closing and are often subject to inspection by various security patrols during the course of the night. Heretofore, it has been the practice of storeowners to have minimal lighting on during the night and the security officer is required to peer in the window to determine whether or not there is or have been intruders. Applicant herein has recognized that it would be extremely beneficial if the security patrols would have a means, without having to enter the establishment, for turning on bright lights within the establishment in order to inspect the premises from the outside.
On the other hand, when there has been intrusion, it would also be helpful to be able to turn on the inside lights before the patrolman or police enters the establishment in order to inspect same. Heretofore, the patrolman has had to enter with nothing more than a flashlight or the like and to hunt around for a light switch whereby he can illuminate the premises while he completes the inspection. This is not only dangerous from an accidential standpoint but is extremely dangerous if the intruder is still present in the establishment.
The above problem relating to the increased crime rate and the need for being able to illuminate the premises of either the home or business tie hand in hand with the present energy crisis which makes it prohibitive from a power loss standpoint and an ecology standpoint to keep bright lighting around the home or around a business establishment while that establishment is closed.
The energy crisis also dictates the decreased use of lighting for advertising signs and for expressways and the like when they are not being used. Presently, if street lights or advertising signs are to be lighted, they are equipped with ambient light sensing sources which automatically turn on the street lamps or the advertising signs when darkness occurs. Applicant has noted in the case of advertising signs and even street lighting, that a vast amount of energy is wasted since these lights are on all of the time and many times in areas where the streets or highways are lightly travelled during the night hours.
Devices presently available on the market for controlling the lighting or electrical loads are normally operated by the lack of light or by darkness, which has the apparent disadvantage of wasting vast amounts of valuable energy since these devices stay on throughout the entire period of darkness.